/*
 * Copyright 2015 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
package io.netty.channel.epoll;

import io.netty.channel.Channel;
import io.netty.channel.ChannelConfig;
import io.netty.channel.ChannelOutboundBuffer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.unix.DomainSocketAddress;
import io.netty.channel.unix.DomainSocketChannel;
import io.netty.channel.unix.FileDescriptor;
import io.netty.channel.unix.PeerCredentials;
import io.netty.channel.unix.Socket;

import java.net.SocketAddress;

import static io.netty.channel.unix.Socket.newSocketDomain;
import java.io.IOException;

public final class EpollDomainSocketChannel extends AbstractEpollStreamChannel
        implements DomainSocketChannel
{
    private final EpollDomainSocketChannelConfig config = new EpollDomainSocketChannelConfig(
            this);

    private volatile DomainSocketAddress local;

    private volatile DomainSocketAddress remote;

    public EpollDomainSocketChannel()
    {
        super(newSocketDomain(), false);
    }

    /**
     * @deprecated Use {@link #EpollDomainSocketChannel(Channel, Socket)}.
     */
    @Deprecated
    public EpollDomainSocketChannel(Channel parent, FileDescriptor fd)
    {
        super(parent, new Socket(fd.intValue()));
    }

    /**
     * @deprecated Use {@link #EpollDomainSocketChannel(Socket, boolean)}.
     *             <p>
     *             Creates a new {@link EpollDomainSocketChannel} from an
     *             existing {@link FileDescriptor}
     */
    @Deprecated
    public EpollDomainSocketChannel(FileDescriptor fd)
    {
        super(fd);
    }

    public EpollDomainSocketChannel(Channel parent, Socket fd)
    {
        super(parent, fd);
    }

    /**
     * Creates a new {@link EpollDomainSocketChannel} from an existing
     * {@link FileDescriptor}
     */
    public EpollDomainSocketChannel(Socket fd, boolean active)
    {
        super(fd, active);
    }

    @Override
    protected AbstractEpollUnsafe newUnsafe()
    {
        return new EpollDomainUnsafe();
    }

    @Override
    protected DomainSocketAddress localAddress0()
    {
        return local;
    }

    @Override
    protected DomainSocketAddress remoteAddress0()
    {
        return remote;
    }

    @Override
    protected void doBind(SocketAddress localAddress) throws Exception
    {
        fd().bind(localAddress);
        local = (DomainSocketAddress) localAddress;
    }

    @Override
    public EpollDomainSocketChannelConfig config()
    {
        return config;
    }

    @Override
    protected boolean doConnect(SocketAddress remoteAddress,
            SocketAddress localAddress) throws Exception
    {
        if (super.doConnect(remoteAddress, localAddress))
        {
            local = (DomainSocketAddress) localAddress;
            remote = (DomainSocketAddress) remoteAddress;
            return true;
        }
        return false;
    }

    @Override
    public DomainSocketAddress remoteAddress()
    {
        return (DomainSocketAddress) super.remoteAddress();
    }

    @Override
    public DomainSocketAddress localAddress()
    {
        return (DomainSocketAddress) super.localAddress();
    }

    @Override
    protected boolean doWriteSingle(ChannelOutboundBuffer in,
            int writeSpinCount) throws Exception
    {
        Object msg = in.current();
        if (msg instanceof FileDescriptor && Native.sendFd(fd().intValue(),
                ((FileDescriptor) msg).intValue()) > 0)
        {
            // File descriptor was written, so remove it.
            in.remove();
            return true;
        }
        return super.doWriteSingle(in, writeSpinCount);
    }

    @Override
    protected Object filterOutboundMessage(Object msg)
    {
        if (msg instanceof FileDescriptor)
        {
            return msg;
        }
        return super.filterOutboundMessage(msg);
    }

    /**
     * Returns the unix credentials (uid, gid, pid) of the peer <a
     * href=http://man7.org/linux/man-pages/man7/socket.7.html>SO_PEERCRED</a>
     */
    public PeerCredentials peerCredentials() throws IOException
    {
        return fd().getPeerCredentials();
    }

    private final class EpollDomainUnsafe extends EpollStreamUnsafe
    {
        @Override
        void epollInReady()
        {
            switch (config().getReadMode())
            {
                case BYTES:
                    super.epollInReady();
                    break;
                case FILE_DESCRIPTORS:
                    epollInReadFd();
                    break;
                default:
                    throw new Error();
            }
        }

        private void epollInReadFd()
        {
            if (fd().isInputShutdown())
            {
                clearEpollIn0();
                return;
            }
            final ChannelConfig config = config();
            final EpollRecvByteAllocatorHandle allocHandle = recvBufAllocHandle();
            allocHandle.edgeTriggered(isFlagSet(Native.EPOLLET));

            final ChannelPipeline pipeline = pipeline();
            allocHandle.reset(config);
            epollInBefore();

            try
            {
                readLoop: do
                {
                    // lastBytesRead represents the fd. We use lastBytesRead
                    // because it must be set so that the
                    // EpollRecvByteAllocatorHandle knows if it should try to
                    // read again or not when autoRead is
                    // enabled.
                    allocHandle.lastBytesRead(Native.recvFd(fd().intValue()));
                    switch (allocHandle.lastBytesRead())
                    {
                        case 0:
                            break readLoop;
                        case -1:
                            close(voidPromise());
                            return;
                        default:
                            allocHandle.incMessagesRead(1);
                            readPending = false;
                            pipeline.fireChannelRead(new FileDescriptor(
                                    allocHandle.lastBytesRead()));
                            break;
                    }
                }
                while (allocHandle.continueReading());

                allocHandle.readComplete();
                pipeline.fireChannelReadComplete();
            }
            catch (Throwable t)
            {
                allocHandle.readComplete();
                pipeline.fireChannelReadComplete();
                pipeline.fireExceptionCaught(t);
            }
            finally
            {
                epollInFinally(config);
            }
        }
    }
}
